Effect of extender viscosity on the insemination dose for chickens.

When semen was diluted 1:2 with Beltsville poultry semen extender (BPSE) containing 4% (w/v) carboxymethyl cellulose (CMC), seminal viscosity was 14 times greater than that of semen similarly extended with BPSE and 2.2 times more viscous than neat semen. Under these conditions, CMC was not spermicidal (P greater than .05). Increased seminal viscosity did not enhance fertility (P greater than .05) over a 20-day interval following a single insemination of 33 or 100 X 10(6) spermatozoa/hen. In the case of semen extended with BPSE as well as BPSE containing CMC, the insemination dose of 100 x 10(6) spermatozoa gave superior fertility (P less than .05) compared with results of insemination with 33 X 10(6) spermatozoa. However, when fertility data from the 1st wk of egg collection were compiled, there was no difference in fertility (P greater than .05) due to insemination dose. These results demonstrate that although a conventional insemination dose could be reduced in order to use semen more efficiently, increasing seminal viscosity may not be warranted for artificial insemination programs.